U.S. patent number 6,322,640 [Application Number 09/489,969] was granted by the patent office on 2001-11-27 for multiple thermal annealing method for forming antiferromagnetic exchange biased magnetoresistive (mr) sensor element.
This patent grant is currently assigned to Headway Technologies, Inc.. Invention is credited to Jei-Wei Chang, Cherng-Chyi Han, Kochan Ju, Chyu-Jiuh Torng, Hui-Chuan Wang, Rongfu Xiao.
United States Patent |
6,322,640 |
Xiao , et al. |
November 27, 2001 |
Multiple thermal annealing method for forming antiferromagnetic
exchange biased magnetoresistive (MR) sensor element
Abstract
A method for forming a magnetically biased magnetoresistive (MR)
layer. There is first provided a substrate. There is then formed
over the substrate a ferromagnetic magnetoresistive (MR) material
layer. There is then forming contacting the ferromagnetic
magnetoresistive (MR) material layer a magnetic material layer
formed of a first crystalline phase, where the magnetic material
layer is formed of a crystalline multiphasic magnetic material
having the first crystalline phase which does not appreciably
antiferromagnetically exchange couple with the ferromagnetic
magnetoresistive (MR) material layer and a second crystalline phase
which does appreciably antiferromagnetically exchange couple with
the ferromagnetic magnetoresistive (MR) material layer. There is
then annealed thermally while employing a first thermal annealing
method employing an extrinsic magnetic bias field the magnetic
material layer formed of the first crystalline phase to form a
magnetically aligned magnetic material layer formed of the first
crystalline phase. Finally, there is then annealed thermally while
employing a second thermal annealing method without employing an
extrinsic magnetic bias field the magnetically aligned magnetic
material layer formed of the first crystalline phase to form an
antiferromagnetically coupled magnetically aligned magnetic
material layer formed of the second crystalline phase. The method
may be employed for forming non-parallel antiferromagnetically
biased multiple magnetoresistive (MR) layer magnetoresistive (MR)
sensor elements while employing a single antiferromagnetic
material.
Inventors: |
Xiao; Rongfu (Fremont, CA),
Torng; Chyu-Jiuh (Pleasanton, CA), Wang; Hui-Chuan
(Pleasanton, CA), Chang; Jei-Wei (Cupertino, CA), Han;
Cherng-Chyi (San Jose, CA), Ju; Kochan (Fremont,
CA) |
Assignee: |
Headway Technologies, Inc.
(Milpitas, CA)
|
Family
ID: |
23946029 |
Appl.
No.: |
09/489,969 |
Filed: |
January 24, 2000 |
Current U.S.
Class: |
148/308;
29/603.08; 257/E43.006 |
Current CPC
Class: |
B82Y
40/00 (20130101); B82Y 25/00 (20130101); H01L
43/12 (20130101); H01F 41/302 (20130101); H01F
10/3268 (20130101); Y10T 29/49034 (20150115) |
Current International
Class: |
H01L
43/00 (20060101); H01F 10/00 (20060101); H01F
41/30 (20060101); H01L 43/12 (20060101); H01F
41/14 (20060101); H01F 10/32 (20060101); H01F
041/00 () |
Field of
Search: |
;148/108 ;360/113
;29/603.08 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sheehan; John
Attorney, Agent or Firm: Saile; George O. Ackerman; Stephen
B. Szecsy; Alek
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to co-assigned applications: (1) Ser.
No. 09/182,761, filed Oct. 30, 1998, titled "Canted Longitudinal
Patterned Exchange Biased Dual-Stripe Magnetoresistive (DSMR)
Sensor Element and Method for Fabrication Thereof"; (2) Ser. No.
09/182,775, also filed Oct. 30, 1998, titled "Anti-Parallel
Longitudinal Patterned Exchange Biased Dual Stripe Magnetoresistive
(DSMR) Sensor Element and Method for Fabrication Thereof"; and Ser.
No. 09/415,247, filed Oct. 12, 1999, titled "Method for Forming a
Second Antiferromagnetic Exchange-Coupling Layer for
Magnetoresistive (MR) and Giant MR (GMR) Applications," the
teachings and citations from each of which related co-assigned
applications are incorporated herein fully by reference.
Claims
What is claimed is:
1. A method for forming a magnetically biased magnetoresistive (MR)
layer comprising:
providing a substrate;
forming over the substrate a ferromagnetic magnetoresistive (MR)
layer;
forming in contact with the ferromagnetic magnetoresistive (MR)
material layer a magnetic material layer which is a first
crystalline phase of a multiphasic material having at least two
crystalline phases, and wherein said first crystalline phase does
not appreciably antiferromagnetically exchange couple with the
ferromagnetic magnetoresistive (MR) layer;
annealing thermally while employing a first thermal annealing
method employing an extrinsic magnetic bias field the magnetic
material layer formed of the first crystalline phase to form a
magnetically biased magnetic material layer formed of the first
crystalline phase;
annealing thermally while employing a second thermal annealing
method without employing an extrinsic magnetic bias field the
magnetically biased magnetic material layer formed of the first
crystalline phase to form, thereby, a second crystalline phase of
said magnetically biased magnetic material, within which second
phase it is an antiferromagnetic material and becomes
antiferromagnetically coupled to the said ferromagnetic
magnetoresistive (MR) material layer.
2. The method of claim 1 wherein the magnetoresistive (MR) material
layer is formed within a magnetoresistive (MR) sensor element
selected from the group consisting of single stripe
magnetoresistive (SSMR) sensor elements, dual stripe
magnetoresistive (DSMR) sensor elements and spin valve (SVMR)
sensor elements.
3. The method of claim 1 wherein the ferromagnetic magnetoresistive
(MR) material layer is formed of a ferromagnetic magnetoresistive
(MR) material selected from the group consisting of nickel-iron
permalloy alloy ferromagnetic magnetoresistive (MR) materials,
cobalt-iron alloy ferromagnetic magnetoresistive (MR) materials,
other nickel alloy ferromagnetic magnetoresistive (MR) materials,
other iron alloy ferromagnetic magnetoresistive (MR) materials,
cobalt ferromagnetic magnetoresistive (MR) materials, and
composites of those said materials.
4. The method of claim 1 wherein the crystalline multiphasic
magnetic material is selected from the group consisting of
nickel-manganese alloys, platinum-manganese alloys and
platinum-palladium-manganese alloys.
5. The method of claim 1 wherein the ferromagnetic magnetoresistive
(MR) material layer is formed to a thickness of from about 5 to
about 800 angstroms.
6. The method of claim 1 wherein the magnetic material layer is
formed to a thickness of from about 50 to about 500 angstroms.
7. A method for forming a dual stripe magnetoresistive (MR) sensor
element comprising:
providing a substrate;
forming on the substrate a first ferromagnetic magnetoresistive
(MR) material layer magnetically biased by antiferromagnetic
coupling with a first antiferromagnetic material layer;
forming on the antiferromagnetically biased first ferromagnetic
layer a blanket interstripe dielectric layer;
forming on the blanket interstripe dielectric layer a second
ferromagnetic magnetoresistive (MR) material layer;
forming, in contact with the second ferromagnetic magnetoresistive
(MR) material layer a second magnetic material layer which is a
first crystalline phase of a multiphasic material having at least
two crystalline phases, wherein said first crystalline phase does
not appreciably antiferromagnetically exchange couple with the
second ferromagnetic magnetoresistive (MR) material layer;
annealing thermally while employing a first thermal annealing
method employing an extrinsic magnetic bias field the second
magnetic material layer formed in its first crystalline phase to
form a magnetically aligned second magnetic material layer and a
magnetically aligned second ferromagnetic magnetoresistive (MR)
layer;
annealing thermally while employing a second thermal annealing
method without employing an extrinsic magnetic bias field the
magnetically aligned second magnetic material layer formed in its
first crystalline phase to form a second crystalline phase of said
magnetic material layer in which said second crystalline phase said
magnetic material layer is an antiferromagnetic layer
antiferromagnetically coupled to the magnetically aligned second
ferromagnetic magnetoresistive (MR) layer.
8. The method of claim 7 wherein the first ferromagnetic
magnetoresistive (MR) material layer and the second ferromagnetic
magnetoresistive (MR) material layer are formed of a ferromagnetic
magnetoresistive (MR) material selected from the group consisting
of nickel-iron permalloy alloy ferromagnetic magnetoresistive (MR)
materials, cobalt-iron alloy ferromagnetic magnetoresistive (MR)
materials, other nickel alloy ferromagnetic magnetoresistive (MR)
materials, other iron alloy ferromagnetic magnetoresistive (MR)
materials, cobalt ferromagnetic magnetoresistive (MR) materials,
and composites of those said materials.
9. The method of claim 1 wherein the first antiferromagnetic
material layer and the second antiferromagnetic material layer are
formed of an antiferromagnetic material selected from the group
consisting of nickel-manganese alloys, platinum-manganese alloys
and platinum-palladium-manganese alloys.
10. The method of claim 7 wherein the first antiferromagnetic
material layer and the second antiferromagnetic material layer are
formed of a single antiferromagnetic material.
11. The method of claim 7 wherein the antiferromagnetically coupled
magnetically aligned first antiferromagnetic material layer and the
antiferromagnetically coupled magnetically aligned second
antiferromagnetic material layer are magnetically aligned in an
anti-parallel direction.
12. The method of claim 7 wherein the antiferromagnetically coupled
magnetically biased first ferromagnetic magnetoresistive (MR)
material layer is antiferromagnetically coupled with the
antiferromagnetically coupled magnetically biased first
antiferromagnetic material layer incident to thermal annealing
while employing a third thermal annealing method employed before
the first thermal annealing method or the second thermal annealing
method.
13. A method for forming a spin valve magnetoresistive (SVMR)
sensor element comprising:
providing a substrate;
providing a substrate;
forming over the substrate an antiferromagnetically coupled
magnetically biased ferromagnetic pinned layer
antiferromagnetically coupled with a first antiferromagnetic
pinning material layer, said coupling being produced by a first
annealing method in the presence of an extrinsic magnetic
field;
forming over the ferromagnetic pinned layer a ferromagnetic free
layer, said ferromagnetic free layer being separated from said
ferromagnetic pinned layer by a non-magnetic spacer layer;
forming in magnetic contact with the ferromagnetic free layer a
second magnetic material layer which is a first crystalline phase
of a multiphasic material having at least two crystalline phases,
wherein said first crystalline phase does not appreciably
antiferromagnetically exchange couple with the ferromagnetic free
layer;
annealing thermally while employing a second thermal annealing
method employing an extrinsic magnetic bias field the second
magnetic material layer formed in its first crystalline phase to
form a magnetically aligned second magnetic material layer;
annealing thermally while employing a third thermal annealing
method without employing an extrinsic magnetic bias field the
magnetically aligned second magnetic material layer formed in its
first crystalline phase to form a second crystalline phase of said
magnetic material layer in which said second crystalline phase said
magnetic material layer is an antiferromagnetic layer
antiferromagnetically coupled to the ferromagnetic free layer.
14. The method of claim 13 wherein the ferromagnetic free layer and
the ferromagnetic pinned layer are formed of a ferromagnetic
magnetoresistive (MR) material selected from the group consisting
of nickel-iron permalloy alloy ferromagnetic magnetoresistive (MR)
materials, cobalt-iron alloy ferromagnetic magnetoresistive (MR)
materials, other nickel alloy ferromagnetic magnetoresistive (MR)
materials, other iron alloy ferromagnetic magnetoresistive (MR)
materials, cobalt ferromagnetic magnetoresistive (MR) materials,
and composites of those said materials.
15. The method of claim 13 wherein the antiferromagnetic pinning
material layer and the second antiferromagnetic material layer are
formed of an antiferromagnetic material selected from the group
consisting of nickel-manganese alloys, platinum-manganese alloys
and platinum-palladium-manganese alloys.
16. The method of claim 13 wherein the antiferromagnetic pinning
material layer and the second antiferromagnetic material layer are
formed of the same antiferromagnetic material.
17. The method of claim 13 wherein the first antiferromagnetic
pinning material layer and the second magnetic material layer are
magnetically aligned in mutually perpendicular directions.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods for fabricating
magnetic sensor elements. More particularly, the present invention
relates to methods for fabricating non-parallel magnetically biased
multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor
elements.
2. Description of the Related Art
The recent and continuing advances in computer and information
technology have been made possible not only by the correlating
advances in the functionality, reliability and speed of
semiconductor integrated circuits, but also by the correlating
advances in the storage density and reliability of direct access
storage devices (DASDs) employed in digitally encoded magnetic data
storage and retrieval.
Storage density of direct access storage devices (DASDs) is
typically determined as areal storage density of a magnetic data
storage medium formed upon a rotating magnetic data storage disk
within a direct access storage device (DASD) magnetic data storage
enclosure. The areal storage density of the magnetic data storage
medium is defined largely by the track width, the track spacing and
the linear magnetic domain density within the magnetic data storage
medium. The track width, the track spacing and the linear magnetic
domain density within the magnetic data storage medium are in turn
determined by several principal factors, including but not limited
to: (1) the magnetic read-write characteristics of a magnetic
read-write head employed in reading and writing digitally encoded
magnetic data from and into the magnetic data storage medium; (2)
the magnetic domain characteristics of the magnetic data storage
medium; and (3) the separation distance of the magnetic read-write
head from the magnetic data storage medium.
With regard to the magnetic read-write characteristics of magnetic
read-write heads employed in reading and writing digitally encoded
magnetic data from and into a magnetic data storage medium, it is
known in the art of magnetic read-write head fabrication that
magnetoresistive (MR) sensor elements employed within
magnetoresistive (MR) read-write heads are generally superior to
other types of magnetic sensor elements when employed in retrieving
digitally encoded magnetic data from a magnetic data storage
medium. In that regard, magnetoresistive (MR) sensor elements are
generally regarded as superior since magnetoresistive (MR) sensor
elements are known in the art to provide high output digital read
signal amplitudes, with good linear resolution, independent of the
relative velocity of a magnetic data storage medium with respect to
a magnetoresistive (MR) read-write head having the magnetoresistive
(MR) sensor element incorporated therein.
Within the general category of magnetoresistive (MR) sensor
elements, magnetoresistive (MR) sensor elements which employ
multiple magnetoresistive (MR) layers (typically including a pair
of magnetoresistive (MR) layers), such as but not limited to dual
stripe magnetoresistive (DSMR) sensor elements and spin valve
magnetoresistive (SVMR) sensor elements, and in particular
magnetoresistive (MR) sensor elements which employ multiple
magnetoresistive (MR) layers at least one of which is magnetically
biased to provide non-parallel magnetic bias directions of the
multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor
elements, such as nominally anti-parallel longitudinally
magnetically biased dual stripe magnetoresistive (DSMR) sensor
elements and nominally perpendicularly magnetically biased spin
valve magnetoresistive (SVMR) sensor elements, are presently of
considerable interest insofar as the magnetically biased
magnetoresistive (MR) layers employed within such magnetically
biased multiple magnetoresistive (MR) layer magnetoresistive (MR)
sensor elements typically provide enhanced magnetic read signal
amplitude and fidelity in comparison with single stripe
magnetoresistive (MR) sensor elements, non-magnetically biased
multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor
elements and parallel magnetically biased multiple magnetoresistive
(MR) layer magnetoresistive (MR) sensor elements.
While non-parallel magnetically biased multiple magnetoresistive
(MR) layer magnetoresistive (MR) sensor elements such as but not
limited to nominally anti-parallel longitudinally magnetically
biased dual stripe magnetoresistive (DSMR) sensor elements and
nominally perpendicularly magnetically biased spin valve
magnetoresistive (SVMR) sensor elements are thus desirable within
the art of digitally encoded magnetic data storage and retrieval,
non-parallel multiple magnetoresistive (MR) layer magnetoresistive
(MR) sensor elements are nonetheless not fabricated entirely
without problems in the art of magnetoresistive (MR) sensor element
fabrication. In particular, it is often difficult to form
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor elements with optimal and
enhanced magnetic properties since a magnetic biasing of a later
formed magnetoresistive (MR) layer within a non-parallel
magnetically biased multiple magnetoresistive (MR) layer
magnetoresistive (MR) sensor element will often compromise a
magnetic biasing of an earlier formed magnetoresistive (MR) layer
within the non-parallel magnetically biased multiple
magnetoresistive (MR) layer magnetoresistive (MR) sensor
element.
It is thus towards the goal of providing, for use within magnetic
data storage and retrieval, a method for forming a non-parallel
magnetically biased multiple magnetoresistive (MR) layer
magnetoresistive (MR) sensor element with optimal and enhanced
magnetic properties, that the present invention is most generally
directed.
Various methods and resultant magnetoresistive (MR) sensor element
structures have been disclosed in the art of magnetoresistive (MR)
sensor element fabrication for forming magnetically biased
magnetoresistive (MR) sensor elements with enhanced functionality,
enhanced reliability or other desirable properties.
For example, Mao et al., in U.S. Pat. No. 5,764,056, discloses a
spin valve magnetoresistive (SVMR) sensor element which
simultaneously possesses an enhanced thermal stability and an
enhanced pinning field. To realize the foregoing objects, the spin
valve magnetoresistive (SVMR) sensor element employs a pinned
ferromagnetic material layer of thickness less than about 100
angstroms, wherein the pinned ferromagnetic material layer has
formed laminated thereupon a nickel-manganese alloy
antiferromagnetic pinning material layer of thickness less than
about 200 angstroms.
In addition, Uno et al., in U.S. Pat. No. 5,772,794, discloses a
method for forming a spin valve magnetoresistive (SVMR) sensor
element, wherein there is provided an enhanced magnetic anisotropy
within a pinned magnetoresistive (MR) layer within the spin valve
magnetoresistive (SVMR) sensor element. The method realizes the
foregoing object by employing when fabricating the spin valve
magnetoresistive (SVMR) sensor element a final heat treatment step,
where the final heat treatment step employs application of a
magnetic field in a direction perpendicular to a track width
direction of the spin valve magnetoresistive (SVMR) sensor element
so that the pinned magnetoresistive (MR) layer within the spin
valve magnetoresistive (SVMR) sensor element is pinned by a pinning
material layer within the spin valve magnetoresistive (SVMR) sensor
element with the enhanced uniaxial anisotropy.
Further Hoshiya et al., in U.S. Pat. No. 5,843,589, disclose a
magnetoresistive (MR) sensor element, and a magnetic data storage
system which employs the magnetoresistive (MR) sensor element,
where the magnetoresistive (MR) sensor element has an enhanced
exchange coupling and an enhanced thermal stability. To realize the
foregoing objects, the magnetoresistive (MR) sensor element employs
a cobalt or cobalt alloy ferromagnetic material layer having
laminated thereupon an antiferromagnetic material layer formed of a
chromium-manganese based alloy.
Finally, Gill, in U.S. Pat. No. 5,867,351, discloses a spin valve
magnetoresistive (SVMR) sensor element where an antiferromagnetic
pinning material layer within the spin valve magnetoresistive
(SVMR) sensor element pins a ferromagnetic pinned layer with the
spin valve magnetoresistive (SVMR) sensor element with a high
coercivity while simultaneously not significantly impacting the
coercivity of a ferromagnetic free layer within the spin valve
magnetoresistive (SVMR) sensor element. The spin valve
magnetoresistive (SVMR) sensor element realizes the foregoing
object by employing when forming the spin valve magnetoresistive
(SVMR) sensor element the antiferromagnetic pinning material layer
formed of an amorphous magnetic material, such as a
terbium-iron-cobalt amorphous magnetic material or a
samarium-cobalt amorphous magnetic material, which possesses a high
magnetic coercivity and a low magnetic moment.
Desirable within the art of non-parallel magnetically biased
multiple magnetoresistive (MR) layer magnetoresistive (MR) sensor
element fabrication are additional methods and materials which may
be employed for forming non-parallel magnetically biased multiple
magnetoresistive (MR) layer magnetoresistive (MR) sensor elements
with optimal and enhanced magnetic properties.
It is towards the foregoing object that the present invention is
directed.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for
fabricating a non-parallel magnetically biased multiple
magnetoresistive (MR) layer magnetoresistive (MR) sensor element,
where the non-parallel magnetically biased multiple
magnetoresistive (MR) layer magnetoresistive (MR) sensor element is
formed with optimal and enhanced magnetic properties.
A second object of the present invention is to provide a method for
forming a non-parallel magnetically biased multiple
magnetoresistive (MR) layer magnetoresistive (MR) sensor element in
accord with the first object of the present invention, which method
is readily commercially implemented.
In accord with the objects of the present invention, there is
provided by the present invention a method for magnetically biasing
a magnetoresistive (MR) layer. To practice the method of the
present invention, there is first provided a substrate. There is
then formed over the substrate a ferromagnetic magnetoresistive
(MR) material layer. There is then formed contacting the
ferromagnetic magnetoresistive (MR) material layer a magnetic
material layer formed of a first crystalline phase, where the
magnetic material layer is formed of a crystalline multiphasic
magnetic material having the first crystalline phase which does not
appreciably antiferromagnetically exchange couple with the
ferromagnetic magnetoresistive (MR) material layer and a second
crystalline phase which does appreciably antiferromagnetically
exchange couple with the ferromagnetic magnetoresistive (MR)
material layer. There is then annealed thermally while employing a
first thermal annealing method employing an extrinsic magnetic bias
field the magnetic material layer formed of the first crystalline
phase to form a magnetically biased magnetic material layer formed
of the first crystalline phase. There is then annealed thermally
while employing a second thermal annealing method without an
extrinsic magnetic bias field the magnetically biased magnetic
material layer formed of the first crystalline phase to form an
antiferromagnetically coupled magnetically biased magnetic material
layer formed of the second crystalline phase.
The present invention provides a method for fabricating a
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element, where the non-parallel
magnetically biased multiple magnetoresistive (MR) layer
magnetoresistive (MR) sensor element is fabricated with optimal and
enhanced magnetic properties. The method of the present invention
realizes the foregoing objects by employing when forming the
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element a magnetic material
layer formed contacting a ferromagnetic magnetoresistive (MR)
material layer, where the magnetic material layer is formed of a
crystalline multiphasic magnetic material having a first
crystalline phase which does not appreciably antiferromagnetically
exchange couple with the ferromagnetic magnetoresistive (MR)
material layer and a second crystalline phase which does
appreciably antiferromagnetically exchange couple with the
ferromagnetic magnetoresistive (MR) material layer. There is then
annealed thermally while employing a first thermal annealing method
employing an extrinsic magnetic bias field the magnetic material
layer formed of the first crystalline phase to form a magnetically
biased magnetic material layer formed of the first crystalline
phase. There is then annealed thermally while employing a second
thermal annealing method without an extrinsic magnetic bias field
the magnetically biased magnetic material layer formed of the first
crystalline phase to form an antiferromagnetically exchange coupled
magnetically biased magnetic material layer formed of the second
crystalline phase. By employing within the method of the present
invention the two step thermal annealing method, there may be
employed a pair of temperatures within the two step thermal
annealing method such that there is avoided when fabricating a
magnetoresistive (MR) sensor element within which is formed the
magnetoresistive (MR) layer degradation of other layers within the
magnetoresistive (MR) sensor element.
The method of the present invention is readily commercially
implemented. The method of the present invention employs thermal
annealing methods which are generally known in the art of
magnetoresistive (MR) sensor element fabrication. Since it is at
least in part a process control, in conjunction with a materials
selection, within the present invention which provides at least in
part the method of the present invention, rather than the existence
of methods and materials which provides the present invention, the
method of the present invention is readily commercially
implemented.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects, features and advantages of the present invention are
understood within the context of the Description of the Preferred
Embodiment, as set forth below. The Description of the Preferred
Embodiment is understood within the context of the accompanying
drawings, which form a material part of this disclosure,
wherein:
FIG. 1, FIG. 2 and FIG. 3 show a series of schematic air bearing
surface (ABS) view diagrams illustrating the results of forming in
accord with a general embodiment of the present invention which
comprises a first preferred embodiment of the present invention a
magnetoresistive (MR) sensor element in accord with the present
invention.
FIG. 4, FIG. 5, FIG. 6, FIG. 7 and FIG. 8 show a series of
schematic air bearing surface (ABS) view diagrams illustrating the
results of forming in accord with a more specific embodiment of the
present invention which comprises a second preferred embodiment of
the present invention a dual stripe magnetoresistive (DSMR) sensor
element in accord with the present invention.
FIG. 9, FIG. 10, FIG. 11, FIG. 12 and FIG. 13 show a series of
schematic air bearing surface (ABS) view diagrams illustrating the
results of forming in accord with a more specific embodiment of the
present invention which comprises a third preferred embodiment of
the present invention a spin valve magnetoresistive (SVMR) sensor
element in accord with the present invention.
FIG. 14 shows a schematic air bearing surface (ABS) view diagram of
an alternate spin valve magnetoresistive (SVMR) sensor element in
accord with the third preferred embodiment of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention provides a method for fabricating a
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element, where the non-parallel
magnetically biased multiple magnetoresistive (MR) layer
magnetoresistive (MR) sensor element is fabricated with optimal and
enhanced magnetic properties. The method of the present invention
realizes the foregoing objects by employing when forming the
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element a magnetic material
layer formed contacting a ferromagnetic magnetoresistive (MR)
material layer, where the magnetic material layer is formed of a
crystalline multiphasic magnetic material having a first
crystalline phase which does not appreciably antiferromagnetically
exchange couple with the ferromagnetic magnetoresistive (MR)
material layer and a second crystalline phase which does
appreciably antiferromagnetically exchange couple with the
ferromagnetic magnetoresistive (MR) material layer. There is then
annealed thermally while employing a first thermal annealing method
employing an extrinsic magnetic bias field the magnetic material
layer formed of the first crystalline phase to form a magnetically
biased magnetic material layer formed of the first crystalline
phase. There is then annealed thermally while employing a second
thermal annealing method without an extrinsic magnetic bias field
the magnetically biased magnetic material layer formed of the first
crystalline phase to form an antiferromagnetically exchange coupled
magnetically biased magnetic material layer formed of the second
crystalline phase.
By employing within the method of the present invention the two
step thermal annealing method, there may be employed a pair of
temperatures within the two step thermal annealing method such that
there is avoided when fabricating a magnetoresistive (MR) sensor
element within which is formed the magnetoresistive (MR) layer
degradation of other layers within the magnetoresistive (MR) sensor
element.
While the present invention provides most value when forming an
antiferromagnetically biased magnetoresistive (MR) layer within a
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element, as is illustrated
within the Description of the Preferred Embodiments which follow,
the present invention may be employed in antiferromagnetically
biasing magnetoresistive (MR) layers within magnetoresistive (MR)
sensor elements including but not limited to single stripe
magnetoresistive (SSMR) sensor elements, dual stripe
magnetoresistive (DSMR) sensor elements and spin valve
magnetoresistive (SVMR) sensor elements. Similarly, the present
invention may also be employed in antiferromagnetically biasing
magnetoresistive (MR) layers within other types of magnetoresistive
(MR) sensor elements whose specific configurations and dispositions
of magnetoresistive (MR) layers and antiferromagnetic biasing
layers have not yet been contemplated in the art.
As is similarly understood by a person skilled in the art, a
magnetoresistive (MR) sensor element, such as but not limited to a
non-parallel magnetically biased multiple magnetoresistive (MR)
layer magnetoresistive (MR) sensor element fabricated in accord
with the Description of the Preferred Embodiments, may be employed
within a magnetic sensor within magnetic sensor applications
including but not limited to digital magnetic sensor applications
and analog magnetic sensor applications employing magnetic heads
including but not limited to magnetoresistive (MR) read only heads,
merged inductive magnetic write magnetoresistive (MR) read magnetic
heads and non-merged inductive magnetic write magnetoresistive (MR)
read magnetic read-write heads, as employed within magnetic data
storage enclosures including but not limited to direct access
storage device (DASD) magnetic data storage enclosures and linear
access storage device (LASD) magnetic data storage enclosures.
First Preferred Embodiment
Referring now to FIG. 1 to FIG. 3, there is shown a series of
schematic air bearing surface (ABS) view diagrams illustrating the
results of progressive stages of fabrication in accord with a
general embodiment of the present invention which comprises a first
preferred embodiment of the present invention a magnetoresistive
(MR) sensor element in accord with the present invention. Shown in
FIG. 1 is a schematic air bearing surface (ABS) view diagram of the
magnetoresistive (MR) sensor element at an early stage in its
fabrication in accord with the first preferred embodiment of the
present invention.
Shown in FIG. 1 is a substrate 10 having formed thereupon a
magnetically unbiased patterned magnetoresistive (MR) layer 12 in
turn having formed thereupon a pair of magnetically unbiased
patterned longitudinal magnetic biasing layers 14a and 14b.
Within the first preferred embodiment of the present invention with
respect to the substrate 10, although it is known in the art of
magnetoresistive (MR) sensor element fabrication that substrates
may be formed from non-magnetic ceramic materials such as but not
limited to oxides, nitrides, borides and carbides, as well as
homogeneous and heterogeneous mixtures of oxides, nitrides, borides
and carbides, for the first preferred embodiment of the present
invention, the substrate 10 is typically and preferably formed from
a non-magnetic aluminum oxide/titanium carbide ceramic material.
Preferably, the substrate 10 is formed with sufficient dimensions
to allow the substrate 10 to be fabricated into a slider employed
within a magnetic head employed within a direct access storage
device (DASD) magnetic data storage enclosure employed within
digitally encoded magnetic data storage and retrieval, although, as
noted above, a magnetoresistive (MR) sensor element formed in
accord with the present invention may be employed within other
digital magnetic storage and transduction applications, as well as
analog magnetic signal storage and transduction applications.
Although not specifically illustrated within the schematic air
bearing surface (ABS) view diagram of FIG. 1, it is intended within
the first preferred embodiment of the present invention, as well as
additional embodiments of the present invention, that the substrate
10 additionally comprises any of several layers and structures as
are commonly employed within a magnetic head which is formed while
employing the substrate 10. Such additional layers and structures
may include, but are not limited to, magnetic shield layers and
structures, magnetic pole layers and structures and undercoating
layers and structures.
Within the first preferred embodiment of the present invention with
respect to the magnetically unbiased patterned magnetoresistive
(MR) layer 12, the magnetically unbiased patterned magnetoresistive
(MR) layer 12 is preferably formed of a ferromagnetic
magnetoresistive (MR) material as is conventional in the art of
magnetoresistive (MR) sensor element fabrication, such
ferromagnetic magnetoresistive (MR) materials being selected from
the general group of ferromagnetic magnetoresistive (MR) materials
including but not limited to nickel-iron permalloy alloy
ferromagnetic magnetoresistive (MR) materials, cobalt-iron alloy
ferromagnetic magnetoresistive (MR) materials, other nickel alloy
ferromagnetic magnetoresistive (MR) materials, other iron alloy
ferromagnetic magnetoresistive (MR) materials, cobalt ferromagnetic
magnetoresistive (MR) materials, higher order alloys thereof,
composites thereof and composites of higher order alloys thereof
For the first preferred embodiment of the present invention, the
magnetically unbiased patterned magnetoresistive (MR) layer 12 is
typically and preferably formed upon the substrate 10 from a
nickel-iron (80:20; w/w) permalloy alloy ferromagnetic
magnetoresistive (MR) material formed to a thickness of from about
200 to about 800 angstroms, a length (i.e. long axis or "easy"
axis) of from about 0.2 to about 5 microns and a width (i.e. short
axis of "hard" axis) of from about 0.1 to about 3 microns.
Finally, within the first preferred embodiment of the present
invention with respect to the pair of magnetically unbiased
patterned longitudinal magnetic biasing layers 14a and 14b, the
pair of magnetically unbiased patterned longitudinal magnetic
biasing layers 14a and 14b is formed of a crystalline multiphasic
magnetic material which has at minimum: (1) a first crystalline
phase which does not appreciably antiferromagnetically couple with
the magnetically unbiased patterned magnetoresistive (MR) layer 12;
and (2) a second crystalline phase which does appreciably
antiferromagnetically couple with the magnetically unbiased
patterned magnetoresistive (MR) layer 12. By "not appreciably
antiferromagnetically couple" and "appreciably
antiferromagnetically couple" it is intended that there exists at
minimum about a ten fold difference between: (1) a first
antiferromagnetic exchange field between the first crystalline
phase of the magnetically unbiased patterned longitudinal magnetic
biasing layers 14a and 14b in conjunction with the magnetically
unbiased patterned magnetoresistive (MR) layer 12 (which
approximates zero); and (2) a second antiferromagnetic exchange
field between the corresponding layers when fully
antiferromagnetically exchange coupled with the second crystalline
phase of the magnetically unbiased patterned longitudinal magnetic
biasing layers 14a and 14b.
Within the context of the first preferred embodiment of the present
invention, as well as the additional embodiments of the present
invention, there are several magnetic materials which possess the
crystalline multiphasic characteristics which as noted above are
required for the present invention. Such magnetic materials include
but are not limited to nickel-manganese alloy magnetic materials
(which possess a transition temperature from a
non-antiferromagnetic face centered cubic (fcc) phase to an
antiferromagnetic face centered tetragonal (fct) phase at about 240
degrees centigrade), platinum-manganese alloy magnetic materials
(which possess a transition temperature from a
non-antiferromagnetic face centered cubic (fcc) phase to an
antiferromagnetic face centered tetragonal (fct) phase at about 230
degrees centigrade), platinum-palladium-manganese alloy magnetic
materials and higher order alloys thereof Preferably, the pair of
magnetically unbiased patterned longitudinal magnetic biasing
layers 14a and 14b is formed of a nickel-manganese alloy formed to
a thickness of from about 100 to about 500 angstroms upon the
magnetically unbiased patterned magnetoresistive (MR) layer 12.
Referring now to FIG. 2, there is shown a schematic cross-sectional
diagram illustrating the results of further processing of the
magnetoresistive (MR) sensor element whose schematic
cross-sectional diagram is illustrated in FIG. 1.
Shown in FIG. 2 is a schematic cross-sectional diagram of a
magnetoresistive (MR) sensor element otherwise equivalent to the
magnetoresistive (MR) sensor element whose schematic
cross-sectional diagram is illustrated in FIG. 1, but wherein: (1)
the pair of magnetically unbiased patterned longitudinal magnetic
biasing layers 14a and 14b has been magnetically biased to form a
pair of magnetically biased patterned longitudinal magnetic biasing
layers 14a' and 14b'; and (2) the magnetically unbiased patterned
magnetoresistive (MR) layer 12 has been magnetically biased to form
a magnetically biased patterned magnetoresistive (MR) layer 12',
incident to thermal annealing within a first thermal annealing
environment 16 which employs an extrinsic magnetic bias field
H.
Within the present invention and the first preferred embodiment of
the present invention, the pair of magnetically unbiased patterned
longitudinal magnetic biasing layers 14a and 14b is magnetically
biased to form the pair of magnetically biased patterned
longitudinal magnetic bias layers 14a' and 14b' and the
magnetically unbiased patterned magnetoresistive (MR) layer 12 is
magnetically biased to form the magnetically biased patterned
magnetoresistive (MR) layer 12' within the first thermal annealing
environment 16, which employs, in conjunction with the extrinsic
magnetic bias field H, thermal annealing conditions which do not
induce a crystalline phase change in the magnetic material from
which is formed the magnetically biased patterned longitudinal
magnetic biasing layers 14a' and 14b'. Such a crystalline phase
change may be avoided by employing a thermal annealing temperature
below the crystalline phase change temperature for the magnetic
material from which is formed the magnetically biased patterned
longitudinal magnetic biasing layers 14a' and 14b', or in the
alternative, such a crystalline phase change may be avoided by
employing a thermal annealing temperature above the crystalline
phase change temperature for the magnetic material from which is
formed the magnetically biased patterned longitudinal magnetic
biasing layers 14a' and 14b', but for a sufficiently short time
period such that crystalline phase change kinetics preclude such a
crystalline phase change.
Although not specifically illustrated within the schematic air
bearing surface (ABS) view diagram of FIG. 2, under either of the
foregoing two options for the first thermal annealing environment
16 there is not obtained any antiferromagnetic coupling between the
pair of magnetically biased patterned longitudinal magnetic biasing
layers 14a' and 14b' and the magnetically biased patterned
magnetoresistive (MR) layer 12', since there is avoided a pertinent
crystalline phase change when forming from the magnetically
unbiased patterned longitudinal magnetic biasing layers 14a and 14b
the pair of magnetically biased patterned longitudinal magnetic
biasing layers 14a' and 14b'.
Thus, for example, within the first preferred embodiment of the
present when the pair of magnetically biased patterned longitudinal
magnetic biasing layers 14a' and 14b' is formed of a
nickel-manganese alloy magnetic material which has the crystalline
phase transition temperature of about 240 degrees centigrade, there
is typically preferably employed either: (1) a lower temperature
thermal annealing method which employs a thermal annealing
temperature of from about 200 to about 230 degrees centigrade for a
time period of from about 3 to about 5 hours at the extrinsic
magnetic bias field H of from about 150 to about 300 oersteds, or
in the alternative; (2) a higher temperature thermal annealing
method which employs a thermal annealing temperature of from about
250 to about 270 degrees centigrade for a time period of from about
20 to about 40 minutes at the extrinsic magnetic bias field H of
from about 150 to about 300 oersteds.
Referring now to FIG. 3, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the magnetoresistive (MR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 2.
Shown in FIG. 3 is a schematic air bearing surface (ABS) view
diagram of a magnetoresistive (MR) sensor element otherwise
equivalent to the magnetoresistive (MR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 3, but wherein: (1) the pair of magnetically biased patterned
longitudinal magnetic biasing layers 14a' and 14b'; and (2) the
magnetically biased patterned magnetoresistive (MR) layer 12' have
been thermally annealed within a second thermal annealing
environment 18 without an extrinsic magnetic bias field to form:
(1) a corresponding pair of antiferromagnetically coupled
magnetically biased patterned longitudinal magnetic biasing layers
14a" and 14b"; and (2) a corresponding antiferromagnetically
coupled magnetically biased patterned magnetoresistive (MR) Layer
12". Due to the antiferromagnetic coupling between the pair of
antiferromagnetically coupled magnetically biased patterned
longitudinal magnetic biasing layers 14a" and 14b" and the
antiferromagnetically coupled magnetically biased patterned
magnetoresistive (MR) Layer 12", there is provided an exchange bias
field between the foregoing layers.
Within the first preferred embodiment of the present invention and
the additional preferred embodiments of the present invention, the
second thermal annealing environment 18 employs a second thermal
annealing temperature greater than a crystalline transition
temperature of the magnetic material from which is formed the
antiferromagnetically coupled magnetically biased patterned
longitudinal magnetic biasing layers 14a" and 14b", where the
second thermal annealing temperature is preferably employed for a
second thermal annealing time period sufficiently long such that an
optimally high exchange bias field is developed between the pair of
antiferromagnetically coupled magnetically biased patterned
longitudinal magnetic biasing layers 14a" and 14b" and the
antiferromagnetically coupled magnetically biased patterned
magnetoresistive (MR) layer 12", while not otherwise thermally
degrading any other layers or structures within magnetoresistive
(MR) sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 3.
For example and without limitation, when the pair of
antiferromagnetically coupled magnetically biased patterned
longitudinal magnetic biasing layers 14a" and 14b" is formed of a
nickel-manganese magnetic material, the second thermal annealing
environment 18 preferably employs a second thermal annealing
temperature of from about 250 to about 280 degrees centigrade for a
second thermal annealing time period of from about 5 to about 10
hours.
Upon forming the magnetoresistive (MR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 3, there is formed a magnetoresistive (MR) sensor element with
enhanced antiferromagnetic exchange bias, and thus enhanced
magnetic properties. The magnetoresistive (MR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 3 realizes the foregoing objects by employing when forming the
magnetoresistive (MR) sensor element a two step thermal annealing
method wherein: (1) a first thermal annealing step within the two
step thermal annealing method generally employs a lower temperature
in conjunction with an extrinsic magnetic bias field in order to
magnetically bias a magnetically unbiased patterned
magnetoresistive (MR) layer and a pair of magnetically unbiased
patterned longitudinal magnetic biasing layers while not degrading
magnetic properties of other structures or layers within the
magnetoresistive (MR) sensor element, followed by; (2) a second
thermal annealing step within the two step thermal annealing method
in absence of an extrinsic magnetic bias field for
antiferromagnetically coupling the pair of magnetically biased
patterned longitudinal magnetic biasing layers with the
magnetically biased patterned magnetoresistive (MR) layer.
Second Preferred Embodiment
Referring now to FIG. 4 to FIG. 8, there is shown a series of
schematic air bearing surface (ABS) view diagrams illustrating the
results of progressive stages of forming in accord with a more
specific embodiment of the present invention which comprises a
second preferred embodiment of the present invention a dual stripe
magnetoresistive (DSMR) sensor element in accord with the present
invention. Shown in FIG. 4 is a schematic air bearing surface (ABS)
view diagram illustrating the dual stripe magnetoresistive (DSMR)
sensor element at an early stage in its fabrication in accord with
the second preferred embodiment of the present invention.
Shown in FIG. 4, in a first instance, is a substrate 20 having
formed thereupon a magnetically unbiased patterned first
magnetoresistive (MR) layer 22, in turn having formed thereupon a
pair of magnetically unbiased patterned first longitudinal magnetic
biasing layers 24a and 24b.
Within the second preferred embodiment of the present invention
with respect to the substrate 20, the substrate 20 is typically and
preferably formed employing methods, materials and dimensions
analogous or equivalent to the methods, materials and dimensions
employed for forming the substrate 10 within the first preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface (ABS) view diagrams of FIG. 1 to FIG.
3.
Similarly, within the second preferred embodiment of the present
invention with respect to the magnetically unbiased patterned first
magnetoresistive (MR) layer 22, the magnetically unbiased patterned
first magnetoresistive (MR) layer 22 is typically and preferably
formed employing methods, materials and dimensions analogous or
equivalent to the methods, materials and dimensions employed for
forming the magnetically unbiased patterned magnetoresistive (MR)
layer 12 within the first preferred embodiment of the present
invention, as illustrated within the schematic air bearing surface
(ABS) view diagram of FIG. 1.
Finally, within the second preferred embodiment of the present
invention with respect to the pair of magnetically unbiased
patterned first longitudinal magnetic biasing layers 24a and 24b,
the pair of magnetically unbiased patterned first longitudinal
magnetic biasing layers 24a and 24b is typically and preferably
formed employing methods, materials and dimensions analogous or
equivalent to the methods, materials and dimensions employed for
forming the pair of magnetically unbiased patterned longitudinal
magnetic biasing layers 14a and 14b within the first preferred
embodiment of the present invention, as is similarly also
illustrated within the schematic air bearing surface (ABS) view
diagram of FIG. 1.
Shown also within the schematic air bearing surface (ABS) view
diagram of FIG. 4 is a blanket inter-stripe dielectric layer 26
formed upon and covering portions of the substrate 20, the
magnetically unbiased patterned first magnetoresistive (MR) layer
22 and the magnetically unbiased patterned first longitudinal
magnetic biasing layers 24a and 24b, where the blanket inter-stripe
dielectric layer in turn has formed thereupon a magnetically
unbiased patterned second magnetoresistive (MR) layer 28.
Within the second preferred embodiment of the present invention
with respect to the blanket inter-stripe dielectric layer 26, the
blanket inter-stripe dielectric layer 26 may be formed employing
methods and materials as are conventionally employed for forming
dielectric layers within magnetoresistive (MR) sensor elements,
such methods including but not limited to chemical vapor deposition
(CVD) methods, plasma enhanced chemical vapor deposition (PECVD)
methods and physical vapor deposition (PVD) methods through which
may be formed dielectric layers from dielectric materials including
but not limited to silicon oxide dielectric materials, silicon
nitride dielectric materials and aluminum oxide dielectric
materials. For the second preferred embodiment of the present
invention, the blanket inter-stripe dielectric layer 26 is
typically and preferably formed of an aluminum oxide dielectric
material deposited employing a physical vapor deposition (PVD)
method, as is conventional in the art of magnetoresistive (MR)
sensor element fabrication. Typically and preferably, the blanket
inter-stripe dielectric layer 26 is formed to a thickness of from
about 100 to about 800 angstroms.
Finally within the second preferred embodiment of the present
invention with respect to the magnetically unbiased patterned
second magnetoresistive (MR) layer 28, the magnetically unbiased
patterned second magnetoresistive (MR) layer 28 is typically and
preferably formed employing methods, materials and dimensions
analogous or equivalent to the methods, materials and dimensions
employed for forming the magnetically unbiased patterned first
magnetoresistive (MR) layer 22. Typically and preferably, the
magnetically unbiased patterned first magnetoresistive (MR) layer
22 and the magnetically unbiased patterned second magnetoresistive
(MR) layer 28 are formed of a single magnetoresistive (MR)
material.
Referring now to FIG. 5, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the dual stripe magnetoresistive (DSMR) sensor
element whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 4.
Shown in FIG. 5 is a schematic air bearing surface (ABS) view
diagram of a dual stripe magnetoresistive (DSMR) sensor element
otherwise equivalent to the dual stripe magnetoresistive (DSMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 4, but wherein the dual stripe
magnetoresistive (DSMR) sensor element is thermally annealed within
a first thermal annealing environment 32 while employing a first
thermal annealing temperature, a first thermal annealing exposure
time and a first extrinsic magnetic bias field H1 which
magnetically biases the pair of magnetically unbiased patterned
first longitudinal magnetic biasing layers 24a and 24b to form a
pair of antiferromagnetically coupled magnetically biased patterned
first longitudinal magnetic biasing layers 24a' and 24b' which are
simultaneously antiferromagnetically coupled to an
antiferromagnetically coupled magnetically biased patterned first
magnetoresistive (MR) layer 22' which is formed from the
magnetically unbiased patterned first magnetoresistive (MR) layer
22.
Within the first preferred embodiment of the present invention with
respect to the first thermal annealing environment 32, the first
thermal annealing environment 32 is typically and preferably
provided while employing a first thermal annealing temperature, a
first thermal annealing exposure time and the first extrinsic
magnetic bias field H1 which provides for complete
antiferromagnetic coupling between the pair of
antiferromagnetically coupled magnetically biased patterned first
longitudinal magnetic biasing layers 24a' and 24b' and the
antiferromagnetically coupled magnetically biased patterned first
magnetoresistive (MR) layer 22'.
Thus, for example, within the second preferred embodiment of the
present invention when the pair of magnetically unbiased patterned
first longitudinal magnetic biasing layers 24a and 24b is formed of
a nickel-manganese alloy antiferromagnetic longitudinal magnetic
biasing material which has an antiferromagnetic transition
temperature of about 240 degrees centigrade, the first thermal
annealing method typically and preferably employs: (1) a first
thermal annealing temperature of from about 240 to about 330
degrees centigrade; (2) a first thermal annealing exposure time of
from about 1 to about 15 hours; and (3) a first extrinsic magnetic
bias field H1 of from about 400 to about 3000 oersteds.
Although the air bearing surface (ABS) view diagram of FIG. 5
illustrates the magnetically unbiased patterned second
magnetoresistive (MR) layer 28 as present when forming the pair of
antiferromagnetically coupled magnetically biased patterned first
longitudinal magnetic biasing layers 24a' and 24b' and the
antiferromagnetically coupled magnetically biased patterned first
magnetoresistive (MR) layer 22', such is not required within all
process schemes which may be employed for forming the dual stripe
magnetoresistive (DSMR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 5.
Referring now to FIG. 6, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the dual stripe magnetoresistive (DSMR) sensor
element whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 5.
Shown in FIG. 6 is a schematic air bearing surface (ABS) view
diagram of a dual stripe magnetoresistive (DSMR) sensor element
otherwise equivalent to the dual stripe magnetoresistive (DSMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 5, but wherein there is formed upon
the magnetically unbiased patterned second magnetoresistive (MR)
layer 28 a pair of magnetically unbiased patterned second
longitudinal magnetic biasing layers 30a and 30b.
Within the second preferred embodiment of the present invention,
the pair of magnetically unbiased patterned second longitudinal
magnetic biasing layers 30a and 30bis typically and preferably
formed employing methods, materials and dimensions analogous or
equivalent to the methods, materials and dimensions employed for
forming the pair of magnetically unbiased patterned first
longitudinal magnetic biasing layers 24a and 24b. More preferably,
the pair of magnetically unbiased patterned second longitudinal
magnetic biasing layers 30a and 30b, and the pair of magnetically
biased patterned first longitudinal magnetic biasing layers 24a and
24b are formed of a single antiferromagnetic longitudinal magnetic
biasing material.
Referring now to FIG. 7, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the dual stripe magnetoresistive (DSMR) sensor
element whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 6.
Shown in FIG. 7 is a schematic air bearing surface (ABS) view
diagram of a dual stripe magnetoresistive (DSMR) sensor element
otherwise equivalent to the dual stripe magnetoresistive (DSMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 6, but wherein the dual stripe
magnetoresistive (DSMR) sensor element has been thermally annealed
within a second thermal annealing environment 34, while employing a
second extrinsic magnetic bias field H2 nominally anti-parallel
(typically anti-parallel within a skew of from about -10 to about
+10 degrees from purely anti-parallel) to the first magnetic bias
field H1 as illustrated within the schematic air bearing surface
view diagram of FIG. 5, to thus: (1) form from the pair of
magnetically unbiased patterned second longitudinal magnetic
biasing layers 30a and 30b a pair of magnetically biased patterned
second longitudinal magnetic biasing layers 30a' and 30b'; and (2)
form from the magnetically unbiased patterned second
magnetoresistive (MR) layer 28 a magnetically biased patterned
second magnetoresistive (MR) layer 28'. Within the second preferred
embodiment of the present invention, the second thermal annealing
environment 34 is preferably provided employing methods, materials
and conditions analogous or equivalent to the methods, materials
and conditions employed for providing the first thermal annealing
environment 16 employed within the first preferred embodiment of
the present invention as illustrated within the schematic air
bearing surface (ABS) view diagram of FIG. 2.
As is understood by a person skilled in the art, although the
schematic air bearing surface (ABS) view diagram of FIG. 7
illustrates the second extrinsic magnetic bias field H2 as being
nominally antiparallel to the first extrinsic magnetic bias field
H1 as illustrated within the schematic air bearing surface (ABS)
view diagram of FIG. 5, for alternative designs of dual stripe
magnetoresistive (DSMR) sensor elements alternative non-parallel
dispositions of a second extrinsic magnetic bias field (such as the
second extrinsic magnetic bias field H2) may be provided with
respect to a first extrinsic magnetic bias field (such as the first
extrinsic magnetic bias field H1).
Referring now to FIG. 8, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the dual stripe magnetoresistive (DSMR) sensor
element whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 7.
Shown in FIG. 8 is a schematic air bearing surface (ABS) view
diagram of a dual stripe magnetoresistive (DSMR) sensor element
otherwise equivalent to the dual stripe magnetoresistive (DSMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 7, but wherein: (1) the magnetically
biased patterned second longitudinal magnetic biasing layers 30a'
and 30b' have been transformed to form a pair of
antiferromagnetically coupled magnetically biased patterned second
longitudinal magnetic biasing layers 30a" and 30b"; and (2) the
magnetically biased patterned second magnetoresistive (MR) layer
28' has been transformed to form an antiferromagnetically coupled
magnetically biased patterned second magnetoresistive (MR) layer
28", incident to annealing the dual stripe magnetoresistive (DSMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 7 within a third thermal annealing
environment 36, without an extrinsic magnetic bias field.
Within the second preferred embodiment of the present invention,
the third thermal annealing environment 36 is preferably formed
employing methods, materials and conditions analogous or equivalent
to the methods, materials and conditions employed for forming the
second thermal annealing environment 18 within the first preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface (ABS) view diagram of FIG. 3.
Upon forming the dual stripe magnetoresistive (DSMR) sensor element
whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 8, there is formed a dual stripe
magnetoresistive (DSMR) sensor element, which for reasons as
outlined with respect to the first preferred embodiment of the
present invention possesses optimal and enhanced magnetic
properties.
Third Preferred Embodiment
Referring now to FIG. 9 to FIG. 13, there is shown a series of
schematic air bearing surface (ABS) view diagrams illustrating the
results of forming in accord with a more specific embodiment of the
present invention which comprises a third preferred embodiment of
the present invention a spin valve magnetoresistive (SVMR) sensor
element in accord with the present invention. Shown in FIG. 9 is a
schematic air bearing surface (ABS) view diagram of the spin valve
magnetoresistive (SVMR) sensor element at an early stage in its
fabrication in accord with the third preferred embodiment of the
present invention.
Shown in FIG. 9 is a substrate 40 having formed thereover, among
other layers, a seed layer 42, which in turn has formed thereupon a
magnetically unbiased ferromagnetic free layer 44, which it turn
has formed thereupon a non-magnetic conductor spacer layer 46,
which in turn has formed thereupon a magnetically unbiased
ferromagnetic pinned layer 48, which it turn has formed thereupon a
magnetically unbiased pinning material layer 50, which finally in
turn has formed thereupon a capping layer 52, wherein the aggregate
of the foregoing layers forms a spin valve magnetoresistive (SVMR)
stack layer 53.
Within the third preferred embodiment of the present invention with
respect to the substrate 40, the substrate 40 is preferably formed
employing methods, materials and dimensions analogous or equivalent
to the methods, materials and dimensions employed for forming the
substrate 20 within the dual stripe magnetoresistive (DSMR) sensor
element whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 4 to FIG. 8 or the substrate 10 within the
magnetoresistive (MR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 1 to FIG. 3.
Similarly, within the third preferred embodiment of the present
invention with respect to the seed layer 42, although the seed
layer 42 is optional within the third preferred embodiment of the
present invention, the seed layer 42 is preferably formed of a seed
material which facilitates forming the magnetically unbiased
ferromagnetic free layer 44 upon the seed layer 42. Typically and
preferably, the seed layer 42 is formed to a thickness of from
about 10 to about 100 angstroms.
Similarly, within the third preferred embodiment of the present
invention with respect to the magnetically unbiased ferromagnetic
free layer 44 and the magnetically unbiased ferromagnetic pinned
layer 48, each of the magnetically unbiased ferromagnetic free
layer 44 and the magnetically unbiased ferromagnetic pinned layer
48 is formed of a ferromagnetic material, preferably a single
ferromagnetic material, analogous or equivalent to the
ferromagnetic magnetoresistive (MR) materials from which are
formed: (1) the magnetically unbiased patterned first
magnetoresistive (MR) layer 22 and the magnetically unbiased
patterned second magnetoresistive (MR) layer 28 within the second
preferred embodiment of the present invention as illustrated within
the schematic air bearing surface (ABS) view diagram of FIG. 4; and
(2) the magnetically unbiased patterned magnetoresistive (MR) layer
12 within the first preferred embodiment of the present invention
as illustrated within the schematic air bearing surface (ABS) view
diagram of FIG. 1. Typically and preferably, the magnetically
unbiased ferromagnetic free layer 44 is formed to a thickness of
from about 10 to about 110 angstroms while the magnetically
unbiased ferromagnetic pinned layer 48 is formed to a thickness of
from about 5 to about 80 angstroms.
In addition, within the third preferred embodiment of the present
invention with respect to the non-magnetic conductor spacer layer
46, the non-magnetic conductor spacer layer 46 may be formed of
non-magnetic conductor materials as are conventional in the art of
spin valve magnetoresistive (SVMR) sensor element fabrication,
including but not limited to gold, gold alloy, silver, silver
alloy, copper and copper alloy non-magnetic conductor spacer
materials. For the third preferred embodiment of the present
invention, the non-magnetic conductor spacer layer 46 is preferably
formed of a copper containing non-magnetic conductor spacer
material formed to a thickness of from about 10 to about 50
angstroms upon the magnetically unbiased ferromagnetic free layer
44.
In addition, within the third preferred embodiment of the present
invention with respect to the magnetically unbiased pinning
material layer 50, the magnetically unbiased pinning material layer
50 is formed of an antiferromagnetic pinning material generally
equivalent to the antiferromagnetic material from which is formed
the magnetically unbiased longitudinal magnetic biasing layers 14a
and 14b as employed within the first preferred embodiment of the
present invention as illustrated within the schematic
cross-sectional diagram of FIG. 1. Preferably, the magnetically
unbiased pinning material layer 50 is formed to a thickness of from
about 50 to about 300 angstroms.
Finally, within the third preferred embodiment of the present
invention with respect to the capping layer 52, it is known in the
art of spin valve magnetoresistive (SVMR) sensor element
fabrication that capping layers may be formed of non-magnetic
conductor materials generally analogous to the non-magnetic
conductor materials employed for forming non-magnetic conductor
spacer layers within spin valve magnetoresistive (SVMR) sensor
elements, but where such capping layers are generally formed of
non-magnetic conductor materials of higher resistivity in order to
limit current shunting through the capping layer. Such non-magnetic
conductor materials of higher resistivity include, but are not
limited to, tantalum non-magnetic conductor materials. Thus, for
the preferred embodiment of the present invention the capping layer
52 is preferably formed of a tantalum non-magnetic conductor
material formed to a thickness of from about 10 to about 100
angstroms upon the magnetically unbiased pinning material layer 50.
Within the present invention, the capping layer 52 may
alternatively be formed of a material analogous or equivalent to a
material from which is formed the seed layer 42.
Although the capping layer 52 is optional within the spin-valve
magnetoresistive (SVMR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 9, the capping
layer 52 typically provides a barrier which impedes environmental
degradation of underlying layers within the spin-valve
magnetoresistive (SVMR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 9.
Referring now to FIG. 10, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the spin valve magnetoresistive (SVMR) sensor element
whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 9.
Shown in FIG. 10 is a schematic air bearing surface (ABS) view
diagram of a spin valve magnetoresistive (SVMR) sensor element
otherwise equivalent to the spin valve magnetoresistive (SVMR)
sensor element whose schematic air bearing surface (ABS) view
diagram illustrated in FIG. 9, but wherein the spin valve
magnetoresistive (SVMR) sensor element has been thermally annealed
within a first thermal annealing environment 58 while employing a
first thermal annealing method employing a first extrinsic magnetic
bias field H3 perpendicular to the air bearing surface (ABS) of the
spin valve magnetoresistive (SVMR) sensor element to magnetically
bias the magnetically unbiased pinning material layer 50 and form a
magnetically biased pinning material layer 50' while simultaneously
magnetically biasing the magnetically unbiased ferromagnetic pinned
layer 48 to form a magnetically biased ferromagnetic pinned layer
48', thus forming from the spin valve magnetoresistive (SVMR) stack
layer 53 a once thermally annealed spin valve magnetoresistive
(SVMR) stack layer 53'.
Within the third preferred embodiment of the present invention, the
first thermal annealing environment 58 is preferably provided
employing methods, materials and conditions analogous or equivalent
to the methods, materials and conditions employed when providing
the first thermal annealing environment 32 within the second
preferred embodiment of the present invention, as illustrated
within the schematic air bearing surface (ABS) view diagram of FIG.
5.
Referring now to FIG. 11, there is shown a schematic air bearing
surface view diagram illustrating the results of further processing
of the spin valve magnetoresistive (SVMR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 10.
Shown in FIG. 11 is a schematic air bearing surface (ABS) view
diagram of a spin valve magnetoresistive (SVMR) sensor element
otherwise equivalent to the spin valve magnetoresistive (SVMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated within FIG. 10, but wherein there is formed
adjoining a pair of opposite edges of the once thermally annealed
spin valve magnetoresistive (SVMR) stack layer 53': (1) a pair of
magnetically unbiased ferromagnetic liner layers 55a and 55b,
having formed and aligned thereupon; (2) a pair of magnetically
unbiased longitudinal magnetic biasing layers 54a and 54b, in turn
having formed and aligned thereupon; (3) a pair of patterned
conductor lead layers 56a and 56b.
Within the third preferred embodiment of the present invention: (1)
the pair of magnetically unbiased ferromagnetic liner layers 55a
and 55b is preferably formed employing methods and materials
analogous or equivalent to the methods and materials employed for
forming the magnetically unbiased ferromagnetic pinned layer 48 as
illustrated within the schematic air bearing surface (ABS) view
diagram of FIG. 9; and (2) the pair of magnetically unbiased
longitudinal magnetic biasing layers 54a and 54b is preferably
formed employing methods and materials analogous or equivalent to
the methods and materials which are employed for forming the
magnetically unbiased pinning material layer 50 as is illustrated
within the schematic air bearing surface (ABS) view diagram of FIG.
9. Typically and preferably, the pair of magnetically unbiased
ferromagnetic liner layers 55a and 55b and the pair of magnetically
unbiased longitudinal magnetic biasing layers 54a and 54b are
formed to a thickness of from about 100 to about 800 angstroms, in
the aggregate, per laminated pair.
Similarly, within the third preferred embodiment of the present
invention with respect to the pair of conductor lead layers 56a and
56b, the pair of conductor lead layers 56a and 56b is formed of a
conductor lead material as is conventional in the art of
magnetoresistive (MR) sensor element fabrication, such conductor
lead materials including but not limited to gold, gold alloy,
copper, copper alloy, silver, silver alloy, tantalum and tantalum
alloy conductor lead materials. Typically and preferably, the pair
of conductor lead layers 56a and 56b is formed of a laminate of a
gold alloy and a tantalum alloy conductor material, formed to a
thickness of from about 100 to about 1000 angstroms upon the
magnetically unbiased longitudinal magnetic bias layers 54a and
54b.
Referring now to FIG. 12, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the spin valve magnetoresistive (SVMR) sensor element
whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 11.
Shown in FIG. 12 is a schematic air bearing surface (ABS) view
diagram of a spin valve magnetoresistive (SVMR) sensor element
otherwise equivalent to the spin valve magnetoresistive (SVMR)
sensor whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 11, but wherein the pair of magnetically
unbiased ferromagnetic liner layers 55a and 55b and the pair of
magnetically unbiased longitudinal magnetic biasing layers 54a and
54b have been magnetically biased incident to thermal annealing
within a second thermal annealing environment 60 in the presence of
a second extrinsic magnetic bias field H4 nominally perpendicular
to the first extrinsic magnetic bias field H3 (typically within a
skew from purely perpendicular of from about -10 to about +10
degrees) to form a corresponding pair of magnetically biased
ferromagnetic liner layers 55a' and 55b' and a corresponding pair
of magnetically biased longitudinal magnetic biasing layers 54a'
and 54b', which simultaneously magnetically bias and magnetically
couple the magnetically unbiased ferromagnetic free layer 44 to
form the magnetically biased ferromagnetic free layer 44', and thus
form from the once thermally annealed spin valve magnetoresistive
(SVMR) stack layer 53' a twice thermally annealed spin valve
magnetoresistive (SVMR) stack layer 53".
Within the third preferred embodiment of the present invention, the
second thermal annealing environment 60 is provided employing
methods, materials and conditions analogous or equivalent to the
methods, materials and conditions employed when providing the
second thermal annealing environment 34 within the second preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface (ABS) view diagram of FIG. 7 or the
first thermal annealing environment 16 within the first preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface (ABS) view diagram of FIG. 2.
Referring now to FIG. 13, there is shown a schematic air bearing
surface (ABS) view diagram illustrating the results of further
processing of the spin valve magnetoresistive (SVMR) sensor element
whose schematic air bearing surface (ABS) view diagram is
illustrated within FIG. 12.
Shown in FIG. 13 is a schematic air bearing surface (ABS) view
diagram of a spin valve magnetoresistive (SVMR) sensor element
otherwise equivalent to the spin valve magnetoresistive (SVMR)
sensor element whose schematic air bearing surface (ABS) view
diagram is illustrated in FIG. 12, but wherein: (1) the pair of
magnetically biased ferromagnetic liner layers 55a' and 55b' is
transformed into a pair of antiferromagnetically coupled
magnetically biased ferromagnetic liner layers 55a" and 55b"; (2)
the pair of magnetically biased longitudinal magnetic biasing
layers 54a' and 54b', deposited in a first, non-antiferromagnetic
crystalline form, is transformed into a second crystalline form
wherein said biasing layers now have antiferromagnetic properties
and become antiferromagnetically coupled magnetically biased
longitudinal biasing layers 54a" and 54b"; and (3) the magnetically
biased ferromagnetic free layer 44' is transformed into an
antiferromagnetically coupled magnetically biased ferromagnetic
free layer 44", incident to thermal annealing within a third
thermal annealing environment 62 in which there is no external
magnetic field present.
Within the third preferred embodiment of the present invention, the
third thermal annealing environment 62 is provided while employing
methods, materials and conditions analogous or equivalent to the
methods, materials and conditions employed for providing the third
thermal annealing environment 36 within the second preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface (ABS) view diagram of FIG. 8 or the
second thermal annealing environment 18 within the first preferred
embodiment of the present invention as illustrated within the
schematic air bearing surface view diagram of FIG. 3.
Upon forming the spin valve magnetoresistive (SVMR) sensor element
whose schematic air bearing surface (ABS) view diagram is
illustrated in FIG. 13, there is formed a spin valve
magnetoresistive (DSMR) sensor element, which for reasons as
outlined with respect to the first preferred embodiment of the
present invention, possesses optimal and enhanced magnetic
properties.
Referring now to FIG. 14, there is shown a schematic air bearing
surface (ABS) of an alternate spin valve magnetoresistive (SVMR)
sensor element in accord with the third preferred embodiment of the
present invention.
Shown in FIG. 14 is a spin valve magnetoresistive (SVMR) sensor
element otherwise equivalent to the spin valve magnetoresistive
(SVMR) sensor element whose schematic air bearing surface (ABS)
view diagram is illustrated in FIG. 13, but wherein there is
reversed with respect to the non-magnetic conductor spacer layer 46
a positioning of: (1) the antiferromagnetically coupled
magnetically biased ferromagnetic free layer 44"; and (2) the pair
of layers consisting of the antiferromagnetically coupled
magnetically biased ferromagnetic pinned layer 48' and the
antiferromagnetically coupled magnetically biased pinning material
layer 50" to thus form in the alternative of the three times
thermally annealed spin valve magnetoresistive (SVMR) stack layer
53'" as illustrated within the schematic air bearing surface (ABS)
view diagram of FIG. 13 an alternate three times thermally annealed
spin valve magnetoresistive (SVMR) stack layer 53a'".
The spin valve magnetoresistive (SVMR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated in
FIG. 14 may be formed in the alternative of the spin valve
magnetoresistive (SVMR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 13 by simple
substitution of ordering of the above noted layers when fabricating
the spin valve magnetoresistive (SVMR) sensor element whose
schematic air bearing surface (ABS) view diagram is illustrated
within FIG. 14, without otherwise changing the thicknesses of any
of the foregoing layers or the methods for fabrication of any of
the foregoing layers when fabricating the spin-valve
magnetoresistive (SVMR) sensor element whose schematic air bearing
surface (ABS) view diagram is illustrated in FIG. 14.
Although not specifically discussed within the context of any of
the foregoing preferred embodiments of the present invention, any
of the thermal annealing environments employed within the present
invention preferably employs a nitrogen thermal annealing ambient,
although other thermal annealing ambient gases may also be employed
within the present invention.
EXAMPLES
There was obtained a series of three alumina-titanium carbide
substrates and formed upon each substrate was a magnetoresistive
(MR) stack layer comprising: (1) a nickel-chromium-iron seed layer
formed to a thickness of about 65 angstroms from a
nickel-chromium-iron alloy of nickel-chromium-iron weight ratio
about 48:40:12; (2) a magnetically unbiased magnetoresistive (MR)
layer formed upon the seed layer of a nickel-iron (80:20, w:w)
magnetoresistive (MR) material at a thickness of about 80
angstroms; (3) a magnetically unbiased magnetic biasing material
layer formed upon the magnetically unbiased magnetoresistive (MR)
layer of a nickel-manganese (42:58; atomic ratio) antiferromagnetic
material at a thickness of about 250 angstroms; and (4) a cap layer
formed upon the magnetically unbiased magnetic biasing material
layer of tantalum formed to a thickness of about 100 angstroms.
There was then thermally annealed the three magnetoresistive (MR)
stack layers while employing a multistep thermal annealing method
in accord with the preferred embodiment of the present invention.
For a first of the magnetoresistive (MR) stack layers, the thermal
annealing method employed: (1) a first thermal annealing at a
temperature of about 230 degrees centigrade for a time period of
about 5 hours at an extrinsic magnetic bias field of about 250
oersteds, followed by; (2) a second thermal annealing at a
temperature of about 250 degrees centigrade for a time period of
about 10 hours. A second of the three magnetoresistive (MR) stack
layers was thermally annealed at: (1) a first thermal annealing
temperature of about 260 degrees centigrade for a time period of
about 0.5 hours at an extrinsic magnetic bias field of about 250
oersteds, followed by; (2) a second thermal annealing at a
temperature of about 260 degrees centigrade for a time period of
about 4.5 hours. Finally, the third magnetoresistive (MR) stack
layer was thermally annealed at a temperature of about 250 degrees
centigrade for a time period of about 10 hours, in absence of an
extrinsic magnetic bias field. Measurements were obtained of
antiferromagnetic exchange field for each magnetoresistive (MR)
stack layers at intervals immediately subsequent to each of the
foregoing thermal annealing exposures, while employing hysteresis
curve measurements as are conventional in the art of
magnetoresistive (MR) sensor element fabrication. The results of
the measurements are reported in Table I, as below.
TABLE I Example Annealing Conditions Measured Exchange Field 1
230C/5 hours/250 Oe 0 Oe 250C/10 hours/0 Oe 377 2 260C/0.5
hours/250 Oe 0 260C/4.5 hours/0 Oe 200 3 250C/10 hours/0 Oe 0
As is seen from review of the data within Table I, there is formed
while employing the method of the present invention a
magnetoresistive (MR) stack layer with substantial exchange bias
while employing a multistep thermal annealing method wherein an
elevated temperature step within the multistep thermal annealing
method is provided without an extrinsic magnetic bias field such
that when thermally annealing the magnetoresistive (MR) stack layer
at the elevated temperature there is avoided degradation of other
layers formed within a magnetoresistive sensor element within which
is employed the magnetoresistive (MR) stack layer.
As is understood by a person skilled in the art, the preferred
embodiments and examples of the present invention are illustrative
of the present invention rather than limiting of the present
invention. Revisions and modifications may be made to methods,
materials, structures and dimensions through which is formed a
magnetoresistive (MR) sensor element, a dual stripe
magnetoresistive (DSMR) sensor element and a spin valve
magnetoresistive (SVMR) sensor element in accord with the preferred
embodiments and examples of the present invention while still
providing a magnetoresistive (MR) sensor element in accord with the
present invention, in accord with the appended claims.
* * * * *